Strap tensioning tools employed in connection with securing a tensioned strap loop around a package or other object are commonly of the type wherein overlapping ends of the strap loop are engaged respectively by a feed wheel and an adjacent base mounted gripper plug. Rotation of the feed wheel advances one strap end while the gripper plug holds the other strap end stationary to tighten the strap loop about a package. Both metallic and non-metallic (e.g., plastic) strap are in use with this type of tool.
In a common type of strap tensioning tool currently employed, the feed wheel is mounted from a main frame for bodily movement toward and away from the base portion to load and to release the overlapping strap ends. Normally, this feed wheel is swingably mounted to approach a base mounted gripper plug to provide a relative movement between the feed wheel and gripper plug.
As tension is drawn on the strap by rotation of the feed wheel, a force must be maintained on both of the overlapping strap ends by the gripper plug and feed wheel as the strap contacting the feed wheel is drawn alongside the strap contacting the gripper plug. The force causes the surface of the feed wheel and gripper plug to be impressed into the strap surfaces thereby providing a frictional gripping action. However, too much force over a small area can cause the strap ends to be too deeply penetrated by the surface of the feed wheel and gripper plug creating a severe deformation of the strap ends that can induce premature fracture of the strap. This problem can be aggravated if the surfaces of the feed wheel and gripper plug are rough or toothed, since the tips of some of the teeth can more easily puncture the strap. Thus, in the strapping art, it would be highly desirable if the strapping tool were to apply the biasing force on the overlapping strap ends between the feed wheel and gripper plug uniformly, so that no uneven points of pressure are exerted on a portion of the strap to produce too deep a penetration of the strap which might fracture the strap at the weakened pinch area.